The present invention relates to a device for accelerating projectiles by means of an electrically heated plasma. More particularly, the invention relates to such a device for accelerating projectiles, which is of the type including a launching tube which is closed at one end and in which the projectile and two two spaced electrodes for generating and heating the plasma are disposed, one of the two electrodes being disposed at the closed end of the tube.
It is known that firing devices operating according to electrothermal principles (e.g. U.S. Pat. No. 2,899,864) utilize the conversion of electromagnetic energy to thermal energy. In such firing devices, the hot plasma required to drive the projectile is generated and heated by means of an electric arc combusting the plasma between fixed electrodes. The fixed electrodes are here either disposed on the closed (breechblock) end of the launching tube or are distributed over the length of the tube.
In the case where the electrodes are arranged at the breechblock end, the gas pressure generated at the base of the projectile very quickly takes on a high value which is limited by the strength characteristics of the arc burning chamber, the tube and the projectile. However, during acceleration of the projectile, this pressure quickly decreases because of the flow processes taking place in the tube. In this case, the velocity of the projectile at the open end (muzzle) of the tube is noticeably less than would be possible for acceleration with constant pressure.
If the electrodes are distributed over the length of the tube, this drawback does not occur. In that case, the pressure at the projectile base can be kept almost constant by the controlled and continuous addition of electrical discharges and the resulting evaporation of material immediately behind the projectile. However, such an arrangement requires a multicomponent tube and has the drawback that the expenditures for the tube, and for the energy supply, are extremely high.